Yotaka is shown to have a very close relationship with his sister, even to the point of taking her share of drugs which were given to them for the sake of experimenting in exchange to earn money, despite suspecting that the drugs were harmful. He is shown to have resisted control and stopped attacking for a short period of time when his sister hugged him, showing his love for his sister. He also shouted desperately for Gareki to kill him befoe he harms Tsubame. Tsubame is seen to show tremendous grief as Yotaka vanishes.

Yotaka's grandfather is probably the original cause of their family's destruction. Although they cared for each other a lot, his hospital bills were expensive, and Tsubaki had a hard time balancing her siblings' and grandfather's needs.